The electrocardiogram (ECG or sometimes EKG) is a valuable diagnostic tool used extensively by cardiologists worldwide. The ECG records the electrical activity of the heart detected through small electrodes (leads) placed on the patient's chest, wrists and ankles. An examination in a doctor's office might typically collect readings from twelve electrodes and would normally last only up to half an hour. An alternative is for doctors to issue to patients a monitoring device that they take home and wear for a day or two. In this case, typically data from only one or two leads is collected.
The data from the ECG leads is normally recorded on paper or stored in the monitoring device's memory. In the case of the examination in the doctor's office, a physician or nurse scans the printouts by hand since there is relatively little data. For the home monitoring case, again scanning is mostly performed by hand. This may be feasible for 24 hours worth of data. However, many heart conditions are transient and infrequent, occurring only once a week or even less often. For these cases, days or weeks of monitoring may be required, generating a large amount of data that must be scanned, either by machine or by a trained professional, in order to reveal abnormal conditions.
Thus, most modern ECG machines still rely on a doctor or technician printing out the signal readings and looking through it by hand. This is not only time consuming but could result in important symptoms being overlooked. Furthermore, some ECG machines provide limited analysis of the signal, e.g., heart rate, fibrillation detection and the like.